Learning Objectives (UTERUS)
At the end of this online session you should be able to :
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Describe the location and parts of uterus.
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Describe the normal postion of uterus .
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Describe the peritoneal relations of uterus and formation of rectouterine and uterovesical pouch.
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Describe the location and extent of broad ligament & its parts , round ligament of uterus, uterosacral ligament, pubocervical and transverse cervical(cardinal ligament).
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List the contents of broad ligament.
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List the supports of uterus.
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Name the arterirs that supply the uterus
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Understand the clinical significance of the relation of uterine artery and the ureter .
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List the lymph nodes into which the lymphatics drain from the various parts of the uterus.
What is uterus ? Where is it located ?
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Uterus is inverted pear shaped, hollow , thick walled fibromuscular female reproductive organ.
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It is located in the pelvic cavity between urinary bladder in front and rectum behind.
Note: Shape, size and location, structure of uterus varies depending upon age and and other circumstances such as pregnancy.
What are the parts of Uterus?
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Fundus:Rounded part above the level of entrance of uterine tubes.
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Body(Corpus):Extends fron fundus to the narrow constrcted part called isthmus.
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Isthmus: is the constricted part of the uterus and is about 1 cm or less in length.
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Cervix: Is the lower cylindrical part that opens into the vagina.
Cervix
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Is the lower cylindrical part that opens into the vagina.
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Its cavity communicates with that of body at internal Os and with vagina at external Os.
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It is divided into upper supravaginal and lower vaginal parts.
Changes with age in Uterus
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At birth:
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uterus reaches above the level of the pelvic inlet.
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cervix is larger than the body.
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Puberty:
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it grows rapidly until its adult size and shape are reached.
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After menopause:
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becomes smaller, more fibrous, and paler in colour.
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Changes during pregnancy
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size of the uterus increases tremendously during pregnancy.
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fundus rises above the level of the pubic symphysis in the third month. It reaches supracristal plane in the sixth month and the level of the xiphisternal joint in the eighth month. It descends slightly in the ninth month, when the maximal circumference of the fetal head becomes engaged below the pelvic inlet.
Isthmus
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It resembles the body histologically but shows some differences in its musculature, epithelium, and number of glands. The changes that it undergoes during menstruation are not as marked as those in the body.
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From 2nd month of pregnancy it is it is taken up in the body of uterus and forms the lower uterine segment as called by the obstreticians.
Position of Uterus (when bladder is empty)
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Anteverted: Long axis of cervix is bent forward on the long axis of vagina. The angle of anteversion is 90 degrees.
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Anteflexed: Long axis of body of uterus is bent forward on long axis of cervix. the angle of anti flexion is 170 degree.
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this postion provides suppor to the uterus as it rests anteriorly on urinary bladder.
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These positions are readily altered, especially during distention of the urinary bladder When the bladder is full, the uterus extends upward and backward (retroversion).
Layers of wall of uterus (from inside out)
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Endometrium.
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Myometrium
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Perimetrium
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CAVITY OF UTERUS
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It is wide above at the entrance of the uterine tubes, but it gradually decreases in width as it extends downward to the isthmus.
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It is very narrow in sagittal section, because the anterior and posterior walls are almost in contact.
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The canal of the cervix is narrower at its ends than in its middle.
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A vertical fold is located on its anterior wall and another on its posterior wall. Palmate folds radiate obliquely from these in such a way that those on the anterior wall do not oppose those on the posterior wall. Instead, they fit each other so as to close the canal. They tend to disappear after pregnancy.
Uterine cavity: Note the shape and size in different parts
Hysterosalpingography
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The cavity of the uterus and the canal of the cervix can be viewed radiographically after the introduction through the vagina of a suitable radiopaque material (hysterosalpingography).
Peritoneal Relations of Uterus
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From the anterior surface of middle third of rectum the peritoneum is reflected on to the posterior surface of uterus. It not only covers the uterus and cervix but reacheds down to the level of posterior fornix of vagina. This reflection forms a deep peritoneal pouch i.e. RECTOUTERINE POUCH.
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Perioteum then covers the fundus and anterior surface of body of uterus upto the level of isthmus and then is reflected onto the superior surface of urinary bladder. The reflection forms a shallow peritoneal pouch i.e.UTEROVESICAL POUCH
Ligaments supporting Uterus
The tone of the pelvic floor provides the primary support for the uterus. Some ligaments provide further support, securing the uterus in place. The first three ligaments are attached to the cervix.:
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Cardinal (transverse cervical) Ligament : Located at the base of the broad ligament, the cardinal ligament extends from the cervix to the lateral pelvic walls. It contains the uterine artery.
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Uterosacral Ligament: Extends from the cervix to the sacrum. It provides support to the uterus.
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Pubocervical Ligament: from pubis to anterior surface of cervix
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Broad Ligament: This is a double layer of peritoneum attaching the sides of the uterus to the pelvis.
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Round Ligament: is a narrow, flat band of fibrous tissue that is attached to the uterus just below and in front of the entrance of the uterine tube. A remnant of the gubernaculum it extends from uterus to the labia majora via the inguinal canal. It functions to maintain the anteverted position of the uterus.
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Ovarian Ligament: Joins the ovaries to the uterus.
Vagina
Cervix
Broad Ligament:
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Is a double layer of peritoneum extending from the side of the uterus to the lateral walls of the pelvisattaching the sides of the uterus to the pelvis.
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The two layers are continuous with each other above, where they enclose they the uterine tube.
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The broad ligament encloses between its two layers some loose connective tissue and smooth muscle, collectively called the parametrium.
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It also encloses the uterine tube, the ovarian ligament, part of the round ligament, the uterine artery and vein, the uterovaginal plexus of nerves, and a part of the ureter.
Subdivisions of Broad Ligament
It is divided three regions:
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Mesovarium – projects from the posterior surface of broad ligament to the anterior margin of ovaryn enclosing its neurovascular supply. It does not, however, cover the surface of the ovary itself.
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Mesosalpinx – superior to the mesovarium, enclosing the uterine tubes.
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Mesometrium – rest of the broad ligament ligament of the uterus.
Blood supply of Uterus
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Receives arterial supply from paired uterine arteries supplemented by paired ovarian arteries.
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Uterine artery
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is a branch of anterior division of Internal Iliac artery.
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It passes medially from its origin on the upper aspect of the lateral cervical ligament.
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As it approaches cervix, it gives a descending branch that supplies the cervix and the upper part of the vagina and it then turn upward to run between the layers of the broad ligament, near the lateral margins of the body of the uterus.
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As it ascends, it sends branches to both surfaces of the body.
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The uterine arteries become greatly enlarged during pregnancy and are tortuous after parturition.
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Relation of ureter and uterine artery
Approximately 2cm superior to the ischial spine, the ureters run underneath the uterine artery. During a hysterectomy, where the uterus and uterine artery are removed, the ureter is in danger of being accidentally damaged. The relationship between the two can be remembered using the phrase ‘water under the bridge’.
Lymphatic drainage
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Lymphatic vessels from the fundus and upper part of the body drain into lumbar (or aortic) nodes,
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From the lower part of the body into the external iliac nodes
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From the cervix into the external iliac, internal iliac, and sacral nodes.
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Some vessels from the region of the uterus near the entrance of the uterine tube pas with the round ligament and drain into the superficial inguinal nodes.
Watch the Video on PELVIS